Adjustable seat cushion for a wheelchair

ABSTRACT

The seat of a wheelchair has a back that is deeply contoured to provide lateral support for a user, and which is adjusted to conform to user torsos of various sizes. The seat back has a rigid, curved shell formed by a back panel with separate wings adjustably projecting forward from opposite sides of the back panel. Adjustment of the wings alters the length of curvature of the shell to conform to user torsos of different sizes. A cushion is attached to the shell and has pleated sections which expand and contract as the shell is adjusted.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation of U.S. patent application Ser. No. 10/725,048filed on Dec. 1, 2003.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to wheelchairs, and more particularly tothe back for the seat of the wheelchair.

2. Description of the Related Art

Wheelchairs are commonly used by people who are unable to walk. Thetypical wheelchair has tubular metal frame with large rear wheels ateach side and smaller front wheels which typically swivel. In itssimplest form, the seat of the wheelchair comprises a sheet of materialwhich is hung between two horizontal arms of the frame and a similarvertical sheet of material strung between two vertical posts at the rearof the wheelchair. Such sheets of material are flexible therebyconforming to the contour of the user's body.

This simple seat arrangement can aggravate certain medical conditions ofsome wheelchair users, especially those with spinal abnormalities orinjuries. As a consequence, padded seat backs, such as the one in U.S.Pat. No. 5,149,173, have been developed. This type of seat back has aslightly curved rigid back panel attached to the wheelchair frame and afoam cushion is mounted to the panel. The foam cushion forms a curvedrecess for receiving the back of the person seated in the wheelchair.The curvature of the seat back was relatively shallow in order toaccommodate users having torsos of different sizes. The cushion can notbe adjusted to conform to the contour of different sized torsos.

For wheelchair users requiring more lateral support, small bolsters canbe attached on each side of the seat back. The attachment mechanism forsuch bolsters provides some degree of adjustability, both vertically andhorizontally, with respect to the seat back cushion.

Nevertheless, there still exists a need for a more deeply contoured seatback which would provide greater lateral support for the torso of thewheelchair user. However, such a seat back would require a significantdegree of adjustability in order to accommodate user torsos of varioussizes and contours.

SUMMARY OF THE INVENTION

A seat back for a wheelchair has a rigid, curved shell with a back panelfrom which two wings extend toward the front of the wheelchair. Thefirst wing is fastened in an adjustable position at one side of the backpanel and the second wing fastened in an adjustable position at theother side of back panel. In a preferred embodiment, the back panelcomprises a central portion with a first lateral portion extending at aforward angle from one side, and with a second lateral portion extendingat a forward angle from another side. The first wing is adjustablyfastened to the first lateral portion, and the second wing is adjustablyfastened to the second lateral portion.

A cushion is attached to the shell and has a body of a resilientmaterial, such as a closed cell foam for example. The body comprises acentral section adjacent the central portion of the shell, a firstlateral section adjacent the first wing, and a second lateral sectionadjacent the second wing. Preferably, the body has pleated sectionswhich overlap the lateral portions of the shell. The pleated sectionsallow the width of the cushion to stretch and contract, therebyaccommodating variation in the curvature of the shell due to adjustmentof the wing positions.

A fastener arrangement is provided to attach the rigid shell to thewheelchair frame.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric front view of a wheelchair with a seat backaccording to the present invention;

FIG. 2 is a isometric front view of a shell in the seat back;

FIG. 3 is a rear exploded, isometric view of the shell showing fastenersfor securing to the wheelchair frame;

FIG. 4 is a front view of a cushion body that is incorporated in theseat back; and

FIG. 5 is a top view of the cushion body.

DETAILED DESCRIPTION OF THE INVENTION

With initial reference to FIG. 1, a wheelchair 10 has a tubular metalframe 12 that includes a pair of vertical posts 14 and 16 and twohorizontal members 19. A seat 15 of the wheelchair comprises a seatbottom 18 and a seat back 20. The seat bottom is formed by a sheet offabric hung between the horizontal frame members 19.

The seat back 20 includes a back portion 26 from which two lateralsupports 28 extend on each side toward the front of the wheelchair 10.The back portion 26 and lateral supports 28 form a curved, U-shapedstructure within which the wheelchair user can rest and be supported tothe rear and both sides. The seat back 20 is fabricated with a rigid,curved plastic shell 22 to which a cushion 24 is attached on the front.The rear of the plastic shell 22 is fastened to the vertical posts 14and 16 of the frame 12, as will be described.

Referring to FIG. 2, the shell 22 comprises several pieces 30, 38, and42 of a rigid plastic, for example, adjustably fastened together by hexsocket screws or bolts. Although the shell pieces and their sections areessentially planar, they are angled with respect to one another therebyforming a generally curved shell 22. Specifically, the shell has asingle-piece, back panel 30 formed by a generally planar central portion32 from one side of which a first lateral portion 34 extends at aforward angle. A second lateral portion 36 projects in a similar mannerfrom the opposite side of the back panel 30. A first wing 38 of theshell 22 is attached to the first lateral portion 34 and a second wing42 is secured to the second lateral portion 36. The first and secondwings 38 and 42 each have a pair of elongated apertures 44 through whichhex socket screws or bolts 40 extend from the back of the respectivelateral portion 38 or 42 and are threaded into a mounting bracket 46 tosecure the shell pieces together. The elongated apertures 44 allow theposition of each wing 38 and 42 to be adjusted in the horizontaldirection. In addition, the first and second lateral portions 34 and 36have a vertical row of apertures 48 (see FIG. 3) through which the hexsocket screws or bolts 40 can selectively extend to adjust the verticalposition of each wing 38 and 42. Such horizontal and vertical adjustmentallows the curvature of the shell 22, and thus the seat back 20 ingeneral, to conform to the torso of different sized wheelchair users.

With continuing reference to FIG. 3, four fasteners 50 are attached tothe rear surface of the central portion 32 to secure the seat back 20 tothe frame 12 of the wheelchair 10. Two of those brackets 50 are on eachside of the central portion 32 and engage one of the vertical posts 14and 16 of the wheelchair frame. Each fastener 50 includes an L-shapedbracket 52 that has a long leg 54 with two horizontal slots 56 therethrough. A pair of hex socket screws or bolts 58 pass through the slots56 and through two of a plurality of apertures 60 which are aligned intwo vertical rows in the shell central portion 32, as seen in FIG. 2.Initially each aperture 60 extends only partially through the centralportion 32 from the interior surface which provides a more aestheticallypleasing appearance to the seat back than if all the aperture openedthrough the rear surface that is exposed to view. When the mountinglocation for a fastener 50 has been selected, a tool, such as the Allenwrench, is inserted into the appropriate apertures 60 and used to punchthe aperture through the rear surface of the central portion 32. The hexsocket screws or bolts 58 engage threaded holes in a mounting plate 62on the opposite side of the central portion to secure the L-shapedbracket 52 in place.

A short leg 64 of the L-shaped bracket 52 also has a pair of horizontalslots 66. A mounting hook 68 is attached to the short leg 64 by anotherpair of hex socket screws or bolts 72 that pass through the slots 66 andare threaded into apertures in a plate 74. The mounting hook 68 has acurved portion 70 which snaps around the respective vertical post 14 or16 on one side of the wheelchair frame 12.

The two sets of elongated apertures 56 and 66 enable each fastener 50 tobe adjusted along two orthogonal axes. Specifically, the brackets allowthe seat back 20 to be moved in both horizontal axes, i.e. left to rightand front and back. This adjustability allows the seat back 20 to bemounted on wheelchairs of varying sizes and to be positioned on thewheelchair frame 12 to accommodate the torso of the wheelchair user.

An strap 76 may be attached by hex socket screws 77 and a mounting plate78 through apertures 79 in the upper region of the central portion 32.This provides a place for a hand to grasp the seat back 20 and the wheelchair 10 in general.

The cushion 24 of the seat back 20 shown in FIG. 1 has a foam bodyinside and an outer cover 81. As shown in detail in FIG. 4, the body 80is fabricated from any one of several well known resilient foammaterials, such as a closed cell foam, commonly used in seat cushions.The body 80 is formed initially from a flat piece of that material whichis cut into the shape illustrated, so that when bent, the body conformsto the interior curvature of the shell 22. The body 80 has a centralsection 82 from which first and second lateral sections 84 and 86project on opposite sides. The front surface 85 of the central section82 has a grid of horizontal and vertical channels 88 through which airflows between the body 80 and the cover 81 of the cushion. Thehorizontal channels 88 continue to extend laterally across the first andsecond lateral sections 84 and 86.

The first and second lateral sections 84 and 86 relatively deep V-shapedgrooves 90 extending vertically in their front surfaces and a pluralityof similar vertical grooves 92 in their rear surfaces interleaved withthe grooves 90 in the front surface. The pattern these vertical grooves90 and 92 in the lateral sections 94 and 96 form pleated regions 94 and96 on each side of the body 80.

The body 80 is encased in the cover 81 made of a bidirectionallystretchable fabric to form the completed cushion 24, shown in FIG. 1.The rear surface of the cushion cover 81 is formed of a hook material ofa standard hook and loop fastening system, such as the type sold underthe registered trademark VELCRO. A plurality of patches 98 of the loopcomponent of the fastening system are adhered to the front surfaces ofthe elements 32, 38, and 42 of the shell 22, as shown in FIG. 2.

In order to place the cushion 24 into the shell 22, the cushion isfolded so that the first and second lateral sections 84 and 86 of thebody 80 are folded over the front surface of the central section 82. Thefolded cushion is then placed into the shell so that the central sectionabuts the central portion 32 of the shell. Once the cushion 24 ispressed against the central portion 32, the hook and loop material onthe abutting surfaces engage to hold the cushion in place. The first andsecond lateral sections 84 and 86 of the cushion body then are unfoldedso that their outer edges align with the outer edges of the two wings 38and 42 of the shell 22. This alignment is facilitated by the pleatedportions 94 and 96 of the body 80 which allow the cushion to bend inconformity with the curvature of the shell 22, and the width of thecushion 24 compress or expand. The compressibility and expansibilityenable the cushion to accommodate the variable lengths of shellcurvature due to adjustment of the wing positions. For example, in theillustrated configuration of the shell 22 shown in FIG. 2, the wings 38and 42 are located at the extreme inward position of adjustment, therebycreating the smallest curvature length from the front edge of first wing38 to the front edge of the second wing 42. Alternatively, when the twowings 38 and 42 are located at the extreme outward position, the lengthof shell curvature is several inches greater. This difference in thedistance of curvature, depending upon the adjusted position of the wings38 and 42, is accommodated by the expansion and contraction of thecushion 24 that is permitted by the pleated portions 94 and 96 of thebody 80.

The foregoing description was primarily directed to a preferredembodiment of the invention. Although some attention was given tovarious alternatives within the scope of the invention, it isanticipated that one skilled in the art will likely realize additionalalternatives that are now apparent from disclosure of embodiments of theinvention. Accordingly, the scope of the invention should be determinedfrom the following claims and not limited by the above disclosure.

1-22. (canceled)
 23. A seat cushion for a wheelchair with a seat backthat has a back panel from which a pair of wings project in anadjustable manner from opposite lateral sides wherein adjustment of thepair of wings alters curvature of the seat back, the seat cushioncomprising: a body which stretches and contracts to conform toalteration of the curvature of the seat back; and a fastening system forattaching the body to the seat back of the wheelchair.
 24. The seatcushion as recited in claim 23 wherein the body comprises a centralsection adjacent the back panel, a first lateral section extending fromthe central section, and a second lateral section extending from thecentral section, wherein the first and second lateral sections stretchand contract with changes in positions of the first wing and secondwings with respect to the back panel.
 25. The seat cushion as recited inclaim 24 wherein the first lateral section and the second lateralsection of the body are pleated.
 26. The seat cushion as recited inclaim 23 wherein the body has a first surface with a first plurality ofgrooves extending vertically and a second surface with a secondplurality of grooves interleaved with the first plurality of grooves,wherein the first and second plurality of grooves enable the body tostretch and contract with changes in positions of the first wing andsecond wings.
 27. The seat cushion as recited in claim 23 wherein thebody is formed of a resilient foam material.
 28. The seat cushion asrecited in claim 23 further comprising a cover of stretchable materialencasing the body and to which the fastening system is attached.
 29. Thecushion as recited in claim 23 wherein the fastening system comprises ahook and loop fastener.
 30. A seat cushion for a wheelchair with a seatback that has a back panel from which a first wing and a second wingadjustably project from opposite lateral sides, the seat cushioncomprising: a body of a resilient material having a central section, afirst lateral section extending from the central section, and a secondlateral section extending from the central section; and a fasteningsystem to attach the seat cushion to the seat back wherein the centralsection is adjacent the back panel, first lateral section is adjacentthe first wing, and the second lateral section is adjacent the secondwing.
 31. The seat cushion as recited in claim 30 wherein adjustment ofthe first wing or the second wing with respect to the back panel alterscurvature of the seat back, and wherein the body of the cushionstretches and contracts conforming to alteration of the curvature of theseat back.
 32. The seat cushion as recited in claim 30 furthercomprising a cover of stretchable material encasing the body.
 33. Theseat cushion as recited in claim 30 wherein the first lateral sectionand the second lateral section are pleated.
 34. The seat cushion asrecited in claim 30 wherein the body has a first surface with a firstplurality of grooves extending vertically, and a second surface with asecond plurality of grooves interleaved with the first plurality ofgrooves.
 35. The cushion as recited in claim 30 wherein the fasteningsystem comprises a hook and loop fastener.
 36. A cushion for awheelchair with a seat back that has a back panel from which a firstwing and a second wing adjustably project from opposite lateral sides,the cushion comprising: a body of a resilient material and comprising acentral section adjacent the back panel, a pleated first lateral sectionadjacent the first wing, and a pleated second lateral section adjacentthe second wing.
 37. The cushion as recited in claim 36 furthercomprising a fastening system to attach the cushion to the seat back.38. The cushion as recited in claim 37 wherein the fastening systemcomprises hook and loop fastener components.
 39. The cushion as recitedin claim 36 wherein the cushion further comprises a cover of stretchablematerial encasing the body.
 40. The cushion as recited in claim 36wherein the body has a first surface with a first plurality of groovesextending vertically in the first lateral section and the second lateralsection, and a second surface with a second plurality of groovesinterleaved with the first plurality of grooves.